Sternal retractor

ABSTRACT

Devices and methods for sternal retraction that reduces bleeding from the cut edges of a sternum and reduces fracturing of the sternum during retraction. The devices and methods involve the use of sternal retractor blades having a certain geometry and inserts placed inside the sternal retractor blades during retraction of the sternotomy incision. The blades and inserts act to tamponade the blood flow from the cut sternal edge and reduce fracturing of the sternum during retraction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. application 61/609,662 filed on Mar.12, 2012, and U.S. application Ser. No. 13/786,370 filed on Mar. 5,2013, both of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to medical devices, and morespecifically to a sternal retractor that minimizes blood loss andfractures of the sternum during use of the sternal retractor.

Approximately 1,000,000 cardiac surgical procedures are performedworldwide each year. In the vast majority (>95%) of these procedures,access to the heart is achieved by dividing the sternum, a procedureknown as a sternotomy. The sternum is the “breast bone”, a flat boneapproximately 15 to 25 cm in length, 2 to 3 cm in width, and 8 to 16 mmin thickness. In fact, it consists of three bones connected by fused“joints”: the manubrium is 3 to 6 cm long and is located at the cephaladend, the sternum proper is 12 to 15 cm long, while the xiphoid is 1 to 4cm long and located at the caudal end. The manubrium and sternum arecomposed of thin (1 to 2 mm) outer and inner tables of cortical bone anda wafer-like, spongiform center of cancellous bone in which the bonemarrow resides. Within this bone marrow are numerous venous sinusoids.

Bleeding from the cut sternal edges during a sternotomy can be profuseand prolonged, lasting the duration of the operation, which may be 4 to8 hours. Cardiac surgical patients are usually given a powerfulintravenous anticoagulant, heparin, which prevents the formation ofclots during the operation. Total blood loss from the sternal marrowfrequently exceeds one liter during a cardiac operation. In conventionaloperations performed with the use of the heart-lung machine, this shedblood is suctioned up into the venous reservoir of the heart-lungmachine and then re-infused into the arterial system of the patient. Fatdroplets and other particulate matter is copious within blood shed frombone marrow and these “impurities” are also re-infused into the patient,where they have been implicated as a cause of neurocognitive decline(brain injury), respiratory insufficiency, and renal failure after heartsurgery. Recent reports in the literature have advocated discarding thisshed blood, yet the sheer volume of blood shed from the sternal bonemarrow makes this impractical in most cases. Alternatively, this shedblood may be “washed” in a centrifugal cell scavenge system prior tore-infusing the red blood cell portion. Unfortunately, all other bloodcomponents (platelets, coagulation proteins, serum proteins, etc.) arewasted in this system and derangements in the normal clotting ability ofthe patient often result. In either case, the volume of blood routinelyshed from the sternum during cardiac surgery is a major cause of bloodtransfusion during and after cardiac surgery.

Transfusion associated with cardiac surgery is the single largestcivilian demand for blood transfusion worldwide. Within the US, cardiacsurgery consumes 10 to 15% of all blood provided by the Red Cross. Thus,there is a clear and immediate need for a way to safely reduce thevolume of blood shed from sternal bone marrow during surgical proceduresperformed via sternotomy.

When the surgeon performs a sternotomy to access the heart or othermediastinal structures, the cut edges of the sternum are typically priedapart with a mechanical device known as a sternal retractor. This deviceis typically made of stainless steel and includes left and right armsand a rack and pinion mechanism to move the arms apart or together. Thearms have blades attached thereto, which actually contact or grip thecut edges of the sternum to apply the opening pressure exerted by therack and pinion. While these blades are currently available in differentshapes and sizes to accommodate the numerous different availableretractor systems, none are designed to reduce or prevent bleeding fromthe edges of the sternum.

Another issue with presently used sternal retractors is the issue ofsternal fractures. Presently available blades only contact the centralor middle region of the sternal edge. This applies a large amount ofpressure against a relatively small surface area of the sternum, whichleads to frequent fractures of the sternal edges. These fracturescontribute to increased sternal bleeding and are associated with delayedor incomplete healing and increased risk of sternal wound infection.

Accordingly, there is a need for a sternal retractor that reducesbleeding from the cut sternal edge and that reduces fracture of thesternum.

SUMMARY OF THE INVENTION

In one aspect the present invention provides a device and method toreduce bleeding from a cut sternal edge during surgery performed via asternotomy. In another aspect, the present invention provides a deviceand method to reduce sternal breakage during surgery performed via asternotomy.

A typical sternal retractor has arms that attach to a rack, wherein oneof the arms is fixed and the other is movable via a rack and pinionmechanism. Each arm carries a blade and the blades have sternal engagingsurfaces facing away from each other. During a sternotomy, after thecutting of the sternum, the blades are inserted into the chest incisionso that they rest against the sternal edges. The rack and pinion isengaged, causing the blades to move away from each other, and forcingthe sternal edges to move away from each other. This is continued untila sternal opening is created that is large enough for the surgeon toaccess the inside of the chest.

The present device and method for reducing bleeding from the cut edgesof a sternum involves the use of sternal retractor blades having acertain geometry. The blades act to tamponade the blood flow from thecut sternal edge.

The present device and method for reducing bleeding from the cut edgesof a sternum further optionally involves the use of inserts placedinside the sternal retractor blades during retraction of the sternotomyincision. The inserts preferably conform to the surface of the cutsternal bone and act to tamponade the blood flow from the cut sternaledge.

The present device and method for reducing the incidence of sternalfractures during surgical procedures performed via a sternotomy involvesthe use of sternal retractor blades which extend substantially thelength of the sternum and distribute force across substantially theentire sternum during the sternotomy. Because the force applied to thecut sternum is more evenly distributed across the cut edge, theincidence of sternal fracture is reduced. In addition, the presentdevice and method provide a means to create a trapezoidal opening of thesternal cavity, with a wider opening at the caudal end, which alsoreduces fractures.

In a preferred embodiment, the inserts of the invention are used inretractor blades which extend substantially the length of the sternaledge. In a further preferred embodiment, the retractor blades areconfigured to fit the shape of the cut sternal edge. In a still furtherpreferred embodiment, the inserts are configured to fit the shape of thecut sternal edge. In a preferred embodiment, the retractor provides atrapezoidal opening of the sternal cavity.

Further features and advantages of the invention, as well as thestructure and operation of various embodiments of the invention, aredescribed in detail below with reference to the accompanying drawings.It is noted that the invention is not limited to the specificembodiments described herein. Such embodiments are presented herein forillustrative purposes only. Additional embodiments will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a retractor according to one embodimentof the invention.

FIG. 2 is a perspective view of a retractor blade according to oneembodiment of the invention showing the insert in exploded view.

FIG. 3 is an exploded view of one embodiment of the inventionillustrating a pivot attachment of the blade to a retractor arm.

FIG. 4 is a view of an embodiment of the invention illustrating pivotingretractor arms.

FIG. 5 illustrates the pivot attachment shown in FIG. 4 in greaterdetail.

FIG. 6 illustrates an embodiment of a retractor having pivoting bladesthat can be reversibly employed for a patient.

FIG. 7 is a perspective view of another embodiment of a retractor bladeaccording to the invention.

FIG. 8 is a perspective exploded view showing a preferred embodiment ofthe attachment of an insert to a blade.

FIG. 9 is a perspective view of another embodiment of a retractor andretractor blades as described herein.

FIG. 10 is an additional view of aspects of the embodiment of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

A typical sternal retractor has arms that attach to a rack, wherein oneof the arms is fixed and the other is movable via a rack and pinionmechanism. Each arm carries a blade and the blades have sternal engagingsurfaces facing away from each other. During a surgical procedureperformed via a sternotomy, after the sternum is cut, the blades areinserted into the cut opening so that they rest against the sternaledges. The rack and pinion is engaged, causing the blades to move awayfrom each other and causing the sternal edges to move away from eachother. This is continued until a sternal opening is created that islarge enough for the surgeon to access the inside of the chest.

The present invention is a sternal retractor that reduces bleeding fromthe cut edges of the sternum. The present invention also is a sternalretractor that reduces breakage or fracture of the sternum.

Note that while the present invention is described as relating to asternal retractor having two arms, one of which is fixed and the othermovable, the invention is applicable to other types of retractors andretractors having different configurations of arms. For example, thesternal retractor could have two movable arms.

FIG. 1 illustrates a first embodiment of a sternal retractor accordingto the invention. The retractor 10 includes a rack 12 having a fixed arm14 attached thereto. The rack 12 has a second movable arm 16 alsoconnected thereto. Movable arm 16 has a housing 18 on one end thereofcontaining a pinion gear (not shown). This pinion gear interacts with anumber of teeth 20 on rack 12, functioning as a rack and pinion gear.Rotation of the pinion gear and thus movement of the moving arm 16 alongthe rack 12 is controlled by knob 22.

Retractor blades 24, 25 are attached to the fixed arm 14 and the movingarm 16, respectively. As shown more clearly in FIG. 2, retractor blade25 includes a rigid frame 26 and an attachment clip 28. A connector 30connects the attachment clip 28 to the rigid frame 26. The frame,connector, and attachment clip can be one integral part, two separateparts, or three separate parts. Desirably the two blades 24, 25 aremirror images of each other or they can be different.

Rigid frame 26 is sized and shaped to cover a substantial amount of thecut sternal edge. A substantial amount means that the frame extends theentire length of or at least 50% the length of the cut sternal edge. Ina more preferred embodiment, the rigid frame covers at least 75% (and upto or over 100%) of the sternal edge. Desirably, rigid frame 26 has a“canoe” shape with a floor 32 and two side walls 34, 36 whichsubstantially encase the cut sternal edge. Desirably frame 26 includes aclosed cephalad end 38 and an open caudal end 40. However, the caudalend may also be closed in some embodiments. Floor 32 can be flat orslightly bowed outward or inward.

Since the rigid frame 26 is sized and shaped to cover a substantialamount of the cut sternal edge, its preferred size and shape dependsupon the size and shape of the individual patient. It may be desirableto provide a variety of blades with differently sized and shaped rigidframes. In general however, the rigid frame 26 desirably has a lengthfrom about 7 cm to 25 cm. The rigid frame 26 desirably has a width (fromside wall 34 to side wall 36) between about 1 cm and 3.5 cm. Side walls34 and 36 are desirably about 0.25 to 2.5 cm high. Side walls 34, 36 canbe a consistent height along their lengths or varying heights and can bethe same height or different from each other.

The cephalad end 38 can be closed with a wall that is the same height asthe side walls 34, 36. Alternatively, the cephalad end 38 can have alower wall or can be open with no wall. In one embodiment, the cephaladend has a notch (not shown) on the floor 32. The purpose of the closedend 38 or notch is three-fold; first, to signify to the surgeon or otheroperator that the blade has been inserted and positioned properly;second, to aid in tamponading bleeding from the cut edge of themanubrium; and third, to prevent the retractor blades from slidingcaudad when force is applied to them during trapezoidal opening of thesternotomy incision. As described below, during use the closed end 38 ornotch provides a signal that the frame 26 has been placed over thecephalad end of the cut sternal edge.

Since the angle between the sternum and manubrium (the Angle of Louis)is slightly bent downwards at the cephalad section, the frame 26 isdesirably slightly bent at the cephalad end. Desirably, this angle ofcurvature between the caudal section and the cephalad section is fromabout 5 to 30 degrees. Desirably the caudal section is about 4 to 20 cmin length and the cephalad section is about 3 to 5 cm in length. Theframe may be wider at the cephalad section than the caudal section, toaccommodate the greater thickness of the manubrium.

Blades 24, 25 are attached to the retractor arms 14, 16 via one of anumber of mechanisms. Blade 24 or 25 can simply be bolted to the arm 14or 16 through mating holes in the arm and attachment clip 28. Preferablyhowever, blades 24 and 25 are able to pivot. The sternum is moreresistant to spreading at the cephalad end, and if the same force isapplied across the entire length of blade frame 26 then the cephaladsection is more prone to breaking. Having blades that pivot allows theretractor to open the sternum trapezoidally, wider at the caudal sectionwhere the force needed to open the sternum is lower. Desirably theblades pivot at about 5 to 45 degrees. In a preferred embodiment, thecaudal aspects of the blades pivot 10 to 30 degrees outwards from thecenterline of the retractor.

Blades 24, 25 are thus preferably attached to the retractor arms 14, 16with a pivot attachment. This can be a single attachment point, such asa single rotating pin extending through both the blade attachment clip28 and the arm 14, 16 (and which can also function as the connector 30).Alternately, the blades can be attached with the mechanism shown in FIG.3, in which the blade attachment clip 50 has two pins 52 and 54extending therefrom. The pins have expanded heads 53, 55. The retractorarm 56 has two corresponding receiving holes, one of which is a circularstationary receiving hole 58 and the other is an oblong shaped slidinghole 60. The oblong sliding hole 60 is positioned more cephalad and thestationary hole 58 is positioned more caudal. Each of 58 and 60 has asecond hole 59, 61, respectively, connected thereto through which theheads 53, 55, respectively can pass. The heads 53, 55 cannot passthrough holes 58, 60. The pins 52 and 54 are positioned in the holes 58and 60, respectively, by inserting pins 52, 54 through holes 59, 61 andthen sliding the pins into holes 58, 60.

The blade 48 will pivot when the pin 54 slides in the sliding receivinghole 60. The range of pivot of the blade is restricted by the length ofthe sliding receiving hole 60. The blade 48 is kept in place by the pinheads 53, 55 and using a sliding stitch guide 62 that slides into agroove 64 of the retractor arm 56, thus holding the pins 52 and 54 intoposition.

In another embodiment, trapezoidal opening of the sternum is provided bypivoting retractor arms. As shown in FIG. 4, pivot mechanisms 70 and 71attach the retractor arms 72 and 73 to the rack 74. Retractor arm 73 isa two piece assembly 76, 78 which snaps together and arm 72 preferablyhas the same configuration.

FIG. 5 illustrates the pivot attachment 70 in greater detail. A pin 80rotatably fastens arm 72 to the housing 82. A fixed or adjustable pawl84 mechanically stops the rotation of the arm 72 at the desired anglewhen it meets tab 86 on the end of retractor arm 72. When the retractorblades are inserted into the sternotomy incision the blades are paralleland as the retractor opens the angle of the retractor arm 72 can changeuntil tab 86 hits the pawl 84. FIG. 5 shows the pawl 84 allowing a rangeof motion of the arms 72 and 73 from 0 to 25°. The pawl however canallow a range of motion up to about 45°.

Desirably, the pivot mechanisms described above or otherwise providedare equipped with an adjustable governor mechanism that allows thesurgeon to adjust the desired range of motion of the retractor armsand/or blades either before insertion of the retractor blades into thechest or after insertion, during the spreading of the retractor arms.Desirably this governor allows a range of motion of the arms or bladesbetween about 0 and 45°.

In another embodiment, to provide for a trapezoidal sternal opening, theblades can be nonpivoting and the rack can be curved in thecephalad/caudal direction, so that as the retractor arms are spread theblades open the sternum at an angle defined by the curvature of therack. Desirably, in this embodiment, the rack would be curved such thatS linear inches of the rack allow for about 10 to 30 degrees of arc.

In addition to allowing for distribution of pressure across the sternum,the trapezoidal sternal opening provided by pivoting blades or armsapplies reduced pressure on the clavicles and brachial plexus (a veryimportant set of nerves in the shoulder that innervate the arm). Whenthe sternum is opened the same amount at the manubrium as at the bottom(xiphoid), in a rectangular fashion, excess pressure may be placed onthe brachial plexus, which can cause neuropraxia of the brachial plexis.

In yet another embodiment, the rack can be bent in the antero-posteriordirection at about 10 to 30 degrees, so that it conforms to the roundedanterior surface of the human chest and abdomen. This optional aspect isshown in FIG. 1. Of course, the rack may be both curved in thecephalad/caudal direction and bent in the antero-posterior direction.Another optional feature that further provides for beneficial shaping ofthe retractor to the patient's torso is a slight downward angling of theretractor arms. This feature is illustrated in FIGS. 1 and 4.

In another set of preferred embodiments, the arms of the retractor areremovably attached to the rack and pinion mechanism, such that theblades (attached to or independent of the arms) may be inserted into thesternal incision individually and independent of the rack and then laterconnected to a rack and pinion mechanism. This may facilitate theinsertion of the blades into the sternal incision at the beginning ofthe surgical procedure. This embodiment is shown in FIG. 4 with respectto an embodiment having pivoting retractor arms. However, this featurecan also be employed in other embodiments, such as the embodiment shownin FIG. 1.

Similar to the above described optional embodiment, the blades can beprovided removably attached to the retractor arms, such that the bladesmay be inserted into the sternal incision individually and independentof the arms and rack and then later connected to rack and pinionmechanism. This may facilitate the insertion of the blades into thesternal incision at the beginning of the surgical procedure.

The connector 30 provides for spacing of the rigid frame of the blade 26from the retractor arms 14, 16. The preferred distance of this spacingwill vary depending upon the amount of fat anterior to the patient'ssternum. The sternum may be directly under the patient's skin, thusrequiring a very short connector, or there may be an inch or more of fatbetween the skin and the sternum. It is preferable to use as short aconnector as allowed by the patient's fat layer, since otherwise theretractor attachment clip 28 and arms 14, 16 will protrude above thepatient and interfere with the surgeon's access to the exposed area.Preferably, the connector length will range between 1 and 5 cm.Desirably, connectors of various lengths may be available such as atleast short (1 cm), medium (2.5 cm), and deep (5 cm) connectors.

In one embodiment, as shown in FIG. 2, the retractor blade 24 is asingle element comprising the frame 26, connector 30, and attachmentclip 28. In this embodiment, it may be desirable to provide a pluralityof retractor blades having varying connector lengths and bladewidths/shapes. Alternatively, the retractor blades can be provided withindependent frame, connector, and attachment clip. In this case, it maybe desirable to provide connectors of varying lengths so that retractorblades can be assembled having the desired combination of bladewidth/shape and connector length. The width of the connector may also bevariable. A narrow connector will produce less contact with andsubsequent traction on the skin edges, while a wider connector willresult in more direct contact with and traction on the skin edges. Itmay be desirable to provide connectors of two widths, a narrow connectorof about 1 to 4 cm and a wider connector of about 4 to 12 cm.

FIG. 7 illustrates a second preferred embodiment of a retractor blade.Blade 150 includes a rigid frame 152 and an attachment clip 154. Aconnector 156 connects the attachment clip 154 to the rigid frame 152.The frame, connector, and attachment clip can be one integral part, twoseparate parts, or three separate parts.

Rigid frame 152 is sized and shaped to cover a substantial amount of thecut sternal edge. A substantial amount means that the frame extends theentire length of or at least 50% the length of the cut sternal edge.Desirably, rigid frame 152 has a “canoe” shape with a floor 158 and sidewall 160. The caphalad end 164 can be closed with a wall as shown hereor can be open with no wall. Caudal end 166 is preferably open as shownin FIG. 7 or can also be enclosed with a wall. Side wall 162 extendsonly about 5% of the length of the frame 152 as shown here. Side wall162 can also be absent or extend the fill length of the frame.Preferably in this embodiment, side wall 162 extends about 5 to 20% thelength of the frame 152.

Floor 158 can be flat or slightly bowed outward or inward. Attachmentclip 154 includes two pins 168, 170 for attaching the blade 150 to aretractor arm.

In a preferred embodiment, the device and method for reducing bleedingfrom the cut edge of a sternum involves the use of inserts fixed to thesternal retractor blades so that when the retractor blades are placedinto the sternotomy incision, the inserts contact the cut edge of thesternum forcefully as the retractor is opened and the sternal edges arepried apart. The inserts act to tamponade the blood flow from the cutsternal edge. Preferably, the inserts are sized and shaped to fit withinthe rigid frame of the retractor blades described herein. Thus, theinserts will have generally the same dimensions as the rigid frame.However, the insert may be sized smaller or larger than the rigid frame.

One example of an insert according to the invention is shown in FIG. 2.Insert 100 is sized and shaped symmetrically to rigid frame 26, having asimilarly shaped floor 102, walls 106 and 106, closed cephalad end, 108and open caudal end 110.

The insert 100 in the embodiment shown in FIG. 2 is simply friction fitinto the frame 26. In one embodiment, the frame 26 has an inwardlydirectly lip (not shown) around the top perimeter and the insert 100 isretained by the lip. The insert 100 could be simply pushed into place orslid into the frame 26, from the caudal end, so that it slides under thelip.

An insert can be attached to the rigid frame 26 in a number of ways. Inanother embodiment, the insert can be molded to the frame 26—the frameand insert can be an integral piece. In another embodiment, the insertand frame can each have a fastening material attached thereto which bondto each other, such as Velcro® or double sided tape. Similarly, asnap-on attaching means could securely and removably fasten the insertto the interior of the rigid frame 26 of the retractor blade.

If the insert is disposable but the frame is not it is important that nopart of the insert material or disposable fastener is left in or on theframe after the insert is removed.

FIG. 8 illustrates one preferred method for attaching an insert to aretractor blade frame using one or more mating protrusions andindentations. Protrusions can be in the form of pins and other elementsthat extend from the blade. Indentations can be in the form of holes orother receptacles. Blade 180 is illustrated in mirror image. Insert 182is shown exploded from blade 180. Blade 180 includes elongated slits184, 186, male pins 188, 190, 192, and female indents 194, 196. Insert182 contains two elongated protrusions 198 (the second is not in view)which mate with blade elongated slits 184, 186; three female indents200, 202 (the third is hidden from view) which mate with blade male pins188, 190, 192; and two male pins 204, 206 which mate with blade femaleindents 194, 196.

Prior to use, the insert 182 is attached to the blade 180 by snappingthe male and female elements together. After use, the insert 182 cansimply be peeled off of the frame 180 and disposed. While the blade andinsert are shown here having a multitude of attachment points it shouldbe understood that the invention can employ more or less attachmentpoints, and a different variety of attachment means (slits, tabs,extrusions, male pins, female indents, etc.).

The insert is desirably made of a material that conforms to the surfaceof the cut sternal edge so that a seal is created that reduces oreliminates blood flow. The cut sternal edge has a surface which is anuneven, irregular latticework of cancellous bone, containing sharp bonysurfaces as well as open pores. Desirably, the insert conforms to thesurface so that it tamponades bleeding from the cut surface. By conformsis meant that the insert will adjust its surface to match the surface ofthe sternal edge so that a maximum amount of surface area of the sternaledge is tamponaded by the insert.

In order to provide these functions, the material should exhibit a soft,rubbery, and pliant behavior. Typical materials that are appropriatehave a durometer ranging from about 20 to 60 Shore00 or about 10 to 70Shore A, more desirably between 20 and 40 Shore A. These propertiesminimize the risk of trauma at the material/body interface and allow forgentle removability. In addition, the insert material cannot shred onthe cut bone surface or otherwise leave material on or in the surface ofthe sternal bone or elsewhere in the surgical incision after use. Theinsert is desirably made of a material that is self sealing. The insertmaterial must be biocompatible and sterilizable. The thickness of theinsert should desirably be between about 0.5 to 20 mm.

A number of different materials can be used for the insert, includingsilicones and thermoplastic elastomers. Other materials that may beappropriate for use include some gels, polyurethanes, and rubbers.Examples of materials include Dynaflex™ G2 706-1000-00 by GLSCorporation, Medalist® MD-110 by Teknor Apex, Elastosil® R 427/30 byWacker Chemical Corporation, and LC 58220 by Star Thermoplastic Alloysand Rubbers, Inc., and SILASTICS 9252/250P.

In one embodiment, the insert is supplied as a material that is tastableor moldable. In other words, the insert is provided in a first state andchanges state as it is applied to the cut sternal edge. For example, thematerial could be a material that changes state in response to a changein temperature, exposure to moisture, or upon light activation.

In another embodiment the insert is a dual material—a softer materialsuch as a conformable gel-like material having a tougher skin. In thisway the insert can function as desired as a tamponade but is protectedfrom shredding or otherwise leaving particles upon use.

The insert may include additives such as pro-thrombic agents,antimicrobial agents, analgesic agents, and osteoblastic agents. Thesecan be linked to the insert via known techniques or absorbed into theinsert. Other methods of incorporating additives are known and can beused.

It may be desirable in some cases to use the retractor in the oppositeorientation than that discussed above, where the rack and pinionmechanism is cephalad to the patient rather than caudal. In thissituation it may still be desirable to have retractor blades that rotateand FIG. 6 illustrates one embodiment of a retractor having thisfeature. Retractor 120 includes a rack and pinion mechanism 122.Retractor arms 124, 126 have retractor blades 128, 130, respectively,mounted thereon with the two pin pivot mechanism described above. Inaddition to the circular stationary receiving hole and the oblong shapedsliding hole as described above, this embodiment has a second set ofreceiving holes, a stationary receiving hole 132 and an oblong slidinghole 134. If the retractor is used in the direction having the rack andpinion at the cephalad end, the blades are mounted using this second setof receiving holes 132, 134. Other means of providing reversibleretractors with pivoting arms can also be provided.

In one embodiment, one or more elements of the retractor or blade aredisposable. The insert is desirably disposable. The retractor blade canalso be disposable, whether it is provided as an integral piece with theframe, insert, connector, and attachment clip or whether these parts areprovided individually. In another embodiment, the retractor blade can beprovided as a single piece with the frame, insert, connector, andretractor arm and the entire assembly may be disposable.

FIG. 9 illustrates another preferred embodiment of a retractor 220. Theretractor 220 includes a rack 222 having a fixed arm 224 attachedthereto. The rack 222 has a second movable arm 226 also connectedthereto. Movable arm 226 has a housing 228 on one end thereof containinga pinion gear (not shown). This pinion gear interacts with a number ofteeth 230 on rack 222, functioning as a rack and pinion gear. Rotationof the pinion gear and thus movement of the moving arm 226 along therack 222 is controlled by knob 232.

Retractor blades 234, 235 are attached to the fixed arm 224 and themoving arm 226, respectively, through attachment clips 236, 237,respectively. Attachment clip 236, 237 each is topped with two extendingpins; 238, 239 on clip 236 and 240, 241 on attachment clip 237. In apreferred embodiment, pins 238 and 240 have larger heads than pins 239and 241. As shown more clearly in FIG. 10, retractor arm 226 includes anelongated receiving trough 242 with floor 243 and walls 244, 246. Walls244, 246 are each topped with a retaining lip. In a preferredembodiment, wall 244 is slightly shorter than wall 246.

Four grooves are cut into floor 243, grooves 248, 250, 252, 254. Outergrooves 248, 254 are curved towards each other. In a preferredembodiment, outer grooves 248, 254 are narrower in width than grooves248, 254 so that they can accept pins 239 and 241 but not pins 238 and240. All grooves 248, 250, 252, 254 are open ended at the connection offloor 243 to wall 246.

To mount the blade 235 onto the arm 226 in the direction shown in FIGS.9 and 10, the pin 240 is inserted into groove 250 and the pin 241 isinserted into groove 254. Note that in the preferred embodiment, the pin240 will not fit into groove 248 thus ensuring the blade is mounted withthe pins 240, 241 into grooves 250 and 254.

The curved groove 254 allows for pivoting of the blade 235 up to about5°. The degree of pivot can be adjusted up to about 15° by changing thedistance between the pins 240, 241, and also the distance betweengrooves 250 and 254.

Pins 240, 241 are prevented from slipping out of grooves 250, 254 byinstallation of a sliding suture guard. FIGS. 9 and 10 illustrate thesuture guard 260 in relation to arm 224 and blade 234 but the principleis the same for blade 235 and arm 226. Suture guard 260 includes a body262 having on the top surface thereof one or more suture guides 264.Left gunnel 266 and right gunnel 268 extend along the outside bottomedge of body 262. In a preferred embodiment, left gunnel 266 is slightlyshorter than right gunnel 268. In a preferred embodiment, the end 280 ofthe suture guard 260 is curved.

Suture guide 260 can be slid into the receiving trough of arm 224.Similarly to arm 226, arm 224 includes an elongated receiving trough 270with floor 271 and walls 272, 274. Walls 272, 274 are each topped with aretaining lip. In a preferred embodiment, wall 272 is slightly shorterthan wall 274.

FIG. 9 shows blade 234 attached to the arm 224. The attachment mechanismacts the same as the previously described attachment mechanism for thearm 226 and blade 235. After blade 234 is attached to the arm 224 usingpins 238 and 239, the suture guide 260 is slid into receiving trough270. Note that in the preferred embodiment, suture guide 260 can only beinserted into arm 224, and not arm 226, since the taller right gunnel268 of the suture guide 260 will not fit under the retaining lip of theshorter wall 272 of the arm 224. Insertion of the right-arm suture guideinto the left retractor arm is, for example, prevented.

When suture guide 260 is in place the gunnel 268 blocks the pins 238,239 from sliding out of the grooves. However, the suture guide 260allows free pivoting movement of the pin 239 within the groove.Similarly, when the corresponding suture guide is inserted within thereceiving trough of arm 226 the pins 240, 241 cannot slide out of thegrooves 250, 254 but the pin 241 can freely move within groove 254 andallow pivoting of the blade 235.

Note that this embodiment of the retractor can be used reversibly, asdiscussed above for other embodiments. In other words, typically asternal retractor is used with the rack towards the patient's feet.However on occasion it might be desirable to position the retractor withthe rack closer to the patient's head. In this case, the blades 234, 235can be reversed so that blade 235 is attached to arm 224 and blade 234is attached to arm 226. In the preferred embodiment where the pin 238 islarger and the grooves 248 and 254 are smaller, blade 234 can only bepositioned one way on arm 226 (with pin 238 in groove 252 and pin 239 ingroove 248). Accordingly the blade will be able to pivot.

In one embodiment of the retractor and blade, there is a single pin onthe blade that engages a groove on the retractor arm such that the bladecan pivot on the single pin as the retractor is used to force thesternal edges apart during surgery. The location of the groove on theretractor arm is chosen to optimize the even distribution of force onthe retractor blade as the retractor is cranked open. All other elementsof the retractor, rack and pinion, blade and inserts could be asdescribed elsewhere in this application. In this one-pin design,reversibility of the retractor blade is accomplished simply by switchingthe left and right blades on the right and left retractor arms.

The retractor is put into use after the sternum has been divided with asternal saw or other means. In order to minimize the length of thepost-operative scar, the skin incision may be made shorter than thelength of the sternum. The skin incision is then undermined at itscephalad and caudal ends in order to provide access to divide the entiresternum. In this way, an incision of only 4 to 6 inches is made insteadof 8 to 12 inches. However, although this shortens the length of thescar it makes more difficult the insertion of the long retractor bladesof the invention into the sternotomy incision. Accordingly, the rigidframe is desirably streamlined so that it easily slides into theincision without getting caught up in the skin on either end of theincision. The frame has smooth and rounded edges and is as thin asstructurally possible.

To insert the retractor, the surgeon or other operator lifts the skin atthe cephalad end of the incision and slides the rigid frames of theblades 24, 25 into the incision. The frames are slid until the closedfront end 38 of the frame 26 fits over the cephalad end of the manubrialbone. The skin at the caudal end of the incision can be lifted to allowinsertion of the caudal end of the retractor blades. The presence of theclosed cephalad end 38 or notch as described above provides tactileconfirmation that the blade is properly positioned.

The method of performing a surgical procedure involving a sternotomywith less bleeding thus involves using a sternal retractor having bladesthat extend substantially (at least 50% and preferably at least 75%) thelength of the cut sternal edge. The method further optionally involvesusing a sternal retractor having sternal blades including an insert thatconforms to the cut sternal edge and preferably also coverssubstantially all of the cut sternal edge.

The method of performing a surgical procedure via a sternotomy withlower incidence of sternal fracture involves using a sternal retractorhaving blades that extend substantially (at least 50% and preferably atleast 75%) the length of the cut sternal edge. The method furtheroptionally involves using a retractor with pivoting blades or arms thatopen the sternum to provide a trapezoidal sternal opening.

The above description is for the embodiment where the retractor is fullyassembled before use. As described above, the retractor may be assembledin situ. In such an embodiment, the blades, or just the rigid frame, maybe first inserted into the incision and placed between the cut edges ofthe sternum. In some cases it may be easier to insert just the blades orrigid frame unattached to the retractor arms and rack. Preferably oneblade is inserted into place over the sternal cut edge and then theother blade is placed into position. The blades are then connected tothe retractor arms via one of the connecting methods described above. Ifthe rigid frames are separate pieces they are now connected to theretractor arms via the connectors and attachment clips. In someembodiments, the retractor arms would then have to be connected to therack and pinion mechanism.

Modifications and variations of the present invention will be apparentto those skilled in the art from the forgoing detailed description. Allmodifications and variations are intended to be encompassed by thefollowing claims. All publications, patents, and patent applicationscited herein are hereby incorporated by reference in their entirety.

What is claimed is:
 1. A retractor blade for use with a sternalretractor, wherein the retractor blade comprises: a rigid frameconfigured to attach to a retractor arm; and an insert configured toremovably attach to the rigid frame; wherein the rigid frame is 7 to 25cm in length measured from a caudal end to a cephalad end; and whereinthe rigid frame is configured to at least partially enclose a cutsternal edge and comprising: a floor, and a lower side wall; and whereinthe insert is configured to reduce bleeding from a cut sternal edge. 2.The retractor blade of claim 1, the rigid frame comprising an end wallat the cephalad end.
 3. The retractor blade of claim 2, further having atop side wall that extends from the cephalad end and has a length thatis not more than 20% of the length of the rigid frame.
 4. The retractorblade of claim 1, wherein the length of the rigid frame is 7.5 to 12.5cm.
 5. The retractor blade of claim 1, wherein the length of the rigidframe is 11.25 to 18.75 cm.
 6. The retractor blade of claim 4, whereinthe length of the insert is from 7.5 to 12.5 cm in length.
 7. Theretractor blade of claim 5, wherein the length of the insert is from11.25 to 18.75 cm in length.
 8. The retractor blade of claim 1, whereina width of the rigid frame is 1.0 cm to 3.5 cm.
 9. The retractor bladeof claim 1, wherein the rigid frame comprises: a cephalad section thatis 3 to 5 cm in length; and a caudal section that is longer than thecephalad section and that is about 4 to 20 cm in length; and wherein thecephalad section is at an angle with respect to the caudal section,wherein the angle is 5 to 30 degrees.
 10. The retractor blade of claim1, wherein each of the insert and the rigid frame includes one of eachof one or more pairs of mating protrusions and indentations, wherein theone or more pairs of mating protrusions and indentions removably attachthe insert and the rigid frame.
 11. The retractor blade of claim 1,wherein the insert is conformable to a cut sternal edge.
 12. Theretractor blade of claim 1, wherein the insert: comprises a materialthat conforms to a cut sternal edge; has a durometer ranging from oneof: 20 to 60 Shore 00; or 10 to 70 Shore A; and is biocompatible andsterilizable.
 13. A sternal retractor comprising a first arm and asecond arm and a rack and pinion mechanism to move the first and secondarms away from each other and further comprising a blade of claim 1attached to each arm.
 14. A retractor blade for use with a sternalretractor, wherein the retractor blade comprises: a rigid frameconfigured to attach to a retractor arm, the rigid frame comprising acaudal section at a caudal end of the rigid frame and a cephalad sectionat a cephalad end of the rigid frame; wherein the caudal section islonger than the cephalad section, the cephalad section having a lengthof 3 cm to 5 cm and the caudal section having a length of 4 to 20 cm,wherein an angle between the caudal section and the cephalad section is5 to 30 degrees; wherein the rigid frame has a length that is 7 cm to 25cm wherein the length of the rigid frame includes the length of thecaudal section and the length of the cephalad section; wherein the rigidframe comprises: a floor; and a lower side wall, wherein the rigid frameis configured to at least partially encase a cut sternal edge.
 15. Theretractor blade of claim 14, the rigid frame comprising an end wall atthe the cephalad end.
 16. The retractor blade of claim 14, furthercomprising a top side wall that extends from the cephalad end and has alength that is not more than 20% of the length of the rigid frame. 17.The retractor blade of claim 14, wherein the length of the rigid frameis 7.5 to 12.5 cm.
 18. The retractor blade of claim 14, wherein thelength of the rigid frame is 11.25 to 18.75 cm.
 19. The retractor bladeof claim 14, wherein a width of the rigid frame is 1.0 to and 3.5 cm.20. The retractor blade of claim 14, wherein a width of the rigid frametapers over the length of the rigid frame, with the cephalad end beingwider and the caudal end being narrower.
 21. A sternal retractorcomprising: a first arm and a second arm; a rack and pinion mechanism tomove the first and second arms away from each other; and a retractorblade attached to each arm; wherein a retractor blade is attached to anarm by a pin and groove mechanism which allows the retractor blade topivot on the arm; and wherein the pin and groove mechanism includes afirst pin and a second pin on a retractor blade and a first stationarygroove and a second curved groove on a retractor arm, wherein the firstpin is inserted in the first stationary groove and the second pin isinserted in the second curved groove allowing the retractor blade topivot around the first pin and groove.
 22. The sternal retractor ofclaim 21, wherein the pin and groove attachment is reversible, such thatthe rack and pinion may be positioned either cephalad or caudad.
 23. Thesternal retractor of claim 21, wherein the each retractor blade pivotson a respective one of the retractor arms 0 to 30 degrees away from acenterline of the sternal retractor.